JPH0446620A - Device for controlling speed on stretch reducer mill - Google Patents

Abstract

PURPOSE:To remove the tension applying to the welded part and to prevent the tube from breaking or shape being bad by reducing the speed of the downstream stand at the timing that the position of the welded part of pipe reaches just under the stand, and eliminating the difference of speed between the stands. CONSTITUTION:The tube 2 as the material to be rolled is passed to each stand 1 of the stretch reducer mill and rolled. On this time, the speed compensation starting timing of each stand 1 is decided by trucking the part to be welded 3 with the distance between the top of tube before rolling and the welded part 3, the elongated length of tube 2, the roll diameter of each stand 1, the detected signal of tube top at the inlet and each roll speed signal as the input with the compensation start timing setting device 12. Further, the compensating quantity computing element 14 operates the speed reducing quantity of the downstream stand to be corrected at reaching time to the each stand 1 so that the tension is not applied to the welded part 3 of the tube. Therefore, the tension applied to the welded part 3 is reduced by reducing the speed of the downstream at the timing that the welded part 3 of the tube reaches just under the stand, and eliminating the speed difference between the stands where the welded part 3 exists.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention relates to a speed control device for a stretch reducer mill that rolls a pipe, and particularly relates to a stand speed correction circuit when passing through a welded part. .

(Prior art) A stretch reducer mill is a rolling machine that is composed of a plurality of stands and provides a speed difference between the stands to apply an appropriate tensile force to a pipe, which is a material to be rolled, to obtain a predetermined shape of the pipe. , a longitudinal tensile force always acts on the pipe.

(Problem to be Solved by the Invention) However, in the control method according to the above-mentioned conventional technology, when two pipes are welded and rolled at once, tensile force also acts on the welded part, causing the welded part to break. There is a problem that the shape of the pipe may deteriorate.

The present invention was made in consideration of the above problem, and tracks the position of the pipe weld and reduces the speed of the downstream stand at the timing when the weld reaches directly below the stand, thereby increasing the distance between the stands where the weld is present. The object of the present invention is to provide a speed control device for a stretch reducer mill that eliminates the speed difference, thereby eliminating the tensile force acting on the welded part, and preventing pipe breakage and shape deterioration.

[Structure of the invention]

(Means and Effects for Solving the Problems) The present invention provides a speed control device for a trench reducer mill in which two pipes are welded together and rolled as one pipe through a number of successive rolling stands. A pipe shape setting device that sets the pipe wall pressure, inner diameter, and amount of stretch; an elongation length calculator that calculates the elongation length of the pipe that occurs for each stand from the data set by the pipe shape setting device; Pipe end/m junction initial length setting device to set the length from the previous pipe tip to the welding part, roll diameter setting device to set the roll diameter of each stand,
A pipe detector detects the pipe tip on the entry side of the first stand, the initial length of the pipe end/weld part, the extended length of the pipe, the roll diameter of each stand, the pipe tip detection signal, and the stand roll rotation speed. A correction start timing setting device that tracks the welding part, determines the timing when the welding part comes directly under each stand, and starts speed correction for each stand, a speed reference setting device that sets the roll rotation speed of each stand, and a speed reference setting device for each of the above stands. A correction amount calculator that calculates the speed reduction amount of the downstream stand so that no tensile force is applied to the pipe weld portion when the pipe weld portion passes relative to the speed reference, and corresponds to the speed reduction amount at the correction start timing. It is equipped with a speed reference calculator that corrects the speed of the downstream stand, thereby reducing the tensile force that acts on the weld when the weld passes through stans l~, thereby preventing the weld from breaking. .

(Example) An embodiment of the present invention is shown in FIG.

In FIG. 1, 1 is each stand of a stretch reducer mill, 2 is a pipe which is a material to be rolled, and the two pipes are joined at a welding part 3.

4 is an electric motor that drives each stand 1; 5 is a Leonard device; 6 is a speed detector that detects the speed of each stand; 7 is a roll diameter setting device that sets the roll diameter of each stand; 8 is a respective speed detector that detects the speed of each stand; 9 is a pipe shape setting device for setting the pipe wall thickness, inner diameter and stretch amount in each stand; 9 is a pipe end/weld portion initial length setting device for setting the distance from the tip of the pipe before rolling to the welding portion.

Further, 10 is an elongation length calculator that inputs the data set by the pipe shape setting device 8 and calculates the elongation length of the pipe after rolling; 11 is a pipe detector installed at the entrance of the stand to detect the tip of the pipe; 12 is the distance between the tip of the pipe before rolling and the welding part set by the pipe end/weld part initial length setting device 9, the elongation length of the pipe which is the power of the elongation length calculator 10, and the roll The pipe weld is tracked by inputting the roll diameter of each stand set by the diameter setting device 7, the pipe tip detection signal at the stretch reducer mill inlet detected by the pipe detector 11, and each roll speed signal, and A correction start timing setting device calculates the timing of arrival directly below and determines the speed correction start timing of each stand; 13 is a speed standard setting device that sets a speed standard for each stand; 14 is set by the speed standard setting device 13. The speed standard of each stand is input, and the input speed is corrected when each stand is reached based on the tracking signal of the welded part determined by the correction start timing setting device 12 so that bow tension does not act on the pipe welded part. A correction amount calculator 15 calculates the amount of speed decrease of the downstream stand, and 15 indicates that the welding portion determined by the correction start timing setter according to the amount of speed decrease of each stand calculated by the correction amount calculator is directly below each stand. This is a speed reference calculator that corrects the speed of the downstream stand at the timing when the speed reaches .

In the above configuration, the elongation length calculator 1o calculates the elongation length of the pipe from the pipe shape setting device 8 based on the fact that the elongation length of the pipe is a function of the pipe wall thickness, inner diameter, and amount of stretch in the speed descending pattern shown in FIG. The elongation length after rolling is calculated from the data set in , and the correction start timing setter 12 calculates the timing at which the pipe welded portion reaches directly below each stand using the following formula.

Ti=T0+K・(Li+Q)/vi・DiTill stand arrival timing Li; i stand extension length Q; distance between pipe end/weld part before rolling V; i stand speed; i stand roll diameter To; stand Time K from detection of the inlet pipe end to arrival at the inlet stand; constant Here, L is calculated by the elongation length calculator 10, and Q is set by the pipe end/weld part initial length setting device 9.

vi is the output signal of each speed detector 6, Dl is the value set by the roll diameter setting device 7, and To is the time from when the tip of the pipe is detected until it reaches the inlet stand.

As a result, the speed of the downstream stand is lowered at the timing when the welding part reaches directly below each stand, and the amount of speed decrease is determined by the speed difference of the stand reaching the welding part with respect to the speed reference signal from the speed reference setting device 13. The correction amount calculator 14 determines the amount to be zero.

That is, FIG. 2(A) shows the speed pattern before the welding part reaches the first stand, and at the timing when the welding part reaches the second stand, the speed reference calculator 15 changes to the speed pattern shown in FIG. 2(B). As shown, the speed of the second stand is lowered, and similar speed corrections of the downstream stand are repeated in sequence as the welded portion moves to the downstream stand.

As a result, even when the welded part passes through the rolling stand, rolling is performed without any tensile force acting on the welded part, making it possible to roll the pipe stably without causing pipe breakage.

〔Effect of the invention〕

As explained above, according to the speed control device for a stretch reducer mill according to the present invention, the speed of the downstream stand is lowered at the timing when the pipe weld is tracked and reaches directly under the stand, and the Since the speed difference is eliminated to reduce the tensile force acting on the welded part, and the required tensile force is applied to the pipe parts other than the welded part during rolling, stable pipe rolling without pipe breakage can be achieved. .

[Brief explanation of the drawing]

FIG. 1 is a system diagram showing an embodiment of the speed control device for a stretch reducer mill according to the present invention, and FIGS. 2(A) and (B)
) is a diagram showing a stand speed pattern for explaining the present invention in detail. 1...Rolling stand 2...Welded part of rolled pipe
4. Drive motor Leonard device 6. Speed detector Roll diameter setter 8. Pipe shape setter Pipe end/weld section initial length setter Elongation length calculator 1. Dopipe detector Correction start timing setter Speed standard Setting device 14・Correction amount calculator Speed standard calculator Agent Patent attorney Yoshiaki Inomata (and 1 other person) 2nd group

Claims (1)

[Claims] Pipe shape setting that sets the pipe wall thickness, inner diameter, and amount of stretch for each stand in the speed control device of a stretch reducer mill that welds two pipes and rolls them as one pipe through a number of consecutive rolling stands. An elongation length calculator that calculates the elongation length of the pipe that occurs for each stand from the data set with the pipe shape setting device, and an elongation length calculator that sets the length from the tip of the pipe before being rolled to the welded part. End/weld initial length setting device, roll diameter setting device to set the roll diameter of each stand, pipe detector to detect the pipe tip on the entry side of the first stand, initial length of the above pipe end/weld, pipe The pipe weld is tracked from the extended length of the pipe, the roll diameter of each stand, the pipe tip detection signal, and the stand roll rotation speed, and the timing when the weld comes directly under each stand is determined and the speed correction of each stand is started. Correction start timing setter,
A speed standard setting device that sets the roll rotation speed of each stand, and calculates the speed reduction amount of the downstream stand so that no tensile force is applied to the pipe weld when the pipe weld passes through the speed standard of each stand. A speed control device for a stretch reducer mill, comprising a compensation amount calculator and a speed reference calculator that corrects the speed of a downstream stand corresponding to the speed decrease amount at the correction start timing.